Rotating electrostatic machines



Dec. 24, 1957 B. MENNESSON ROTATING ELECTROSTATIC MACHINES Filed Feb. 5, 1954 ROTATING ELECTROSTATIC MACHINES Bernard Mennesson, Neuilly-sur-Seine,

to Societe dAppareils de des Motenrs (S. A. C. France, a society of France France, assignor Controle et dEquipement E. M.), Neuilly-sur-Seine,

The present invention relates to rotary electrostatic machines working by influences and in particular to machines producing a periodical discharge and it is more especially concerned with spark ignition generators for internal combustion engines.

The chief object of my invention is to eliminate wear and tear due to friction upon one another of parts achieving electrical connections between elements of the machine in relative rotation with respect to each other.

My invention consists chiefly in arranging the machine in such manner that the electrical connections which are to be achieved between electrically influenced plates and electricity collecting plates take place solely through conductor parts leaving between them, when they pass opposite one another, gaps such that electricity can flow therethrough under the effect of the diflerence of potential created by the operation of the machine, these gaps being as a rule lower than 0.08 mm. and ranging preferably from 0.02 to 0.04 mm.

Preferred embodiments of my invention will be hereinafter described with reference to the accompanying drawings, given merely by way of example, and in which the only figure diagrammatically shows in cross section a machine made according to my invention.

My machine essentially comprises two elements in relative rotation with respect to each other, these elements being in the form of cylinders engaged in each other or of discs rotating opposite each other, one of these elements carrying an even number of collecting plates insulated from one another and the other a plurality of influenced plates insulated from one another and which pass successively opposite the first mentioned plates.

In machines of this type, electrical connections must be periodically achieved between plates carried respectively by the two portions which rotate with respect to each other, in particular for earthing the influenced plates at one time during their rotation and for discharging them into the collecting plates at another point of their rotation displacement.

In the machines of this kind which have been known up to the present time, these electrical connections are obtained by means of friction brushes. The friction of these brushes quickly involves a wear and tear which soon becomes prohibitive, in particular in the case of machines used as spark generators. As a matter of fact, in such generators, it is necessary, in order to increase the output, to multiply the number of influenced plates and consequently to dispose these plates in the peripheral zone of cylinders or discs of large diameter, in order to prevent sparks and like phenomena from occurring between one influenced plate and the next one as would be the case if these plates were located too close to one another. Consequently, in machine-s rotating at speeds of several thousands of revolutions per minute, very high relative speeds between the brushes and the conductors exist and Wear and tear takes place very quickly.

In order to obviate this drawback, it has already been proposed in the U. S. patent application Serial No.

United States Patent 2,817,777 Patented Dec. 24, 1957 330,123, filed by Marcel Mennesson on January 7, 1953, for Electrostatic Machines Producing a Periodical Discharge, now Patent 2,685,654, to achieve these electrical connections by means of combs through which the electric charges can pass across a thin layer of a gaseous dielectric and by means of rotating brushes arranged in such manner that they automatically retract under the effect of a physical agent developed by the operation of the machine when the speed of revolution of this machine exceeds a value for which connection can be established through the combs.

Such machines, although constituting a substantial improvement over those existing before them, have however the drawback of not fully eliminating friction, in particular when the machine is being started.

According to my invention, in order to eliminate any friction, the machine is arranged in such manner that all electrical connections between the two elements in relative rotation to each other take place exclusively through conductor parts respectively carried by these elements and arranged to pass opposite one another with extremely small gaps. These gaps are as a rule lower than 0.08 mm. and range preferably from 0.04 to 0.02 mm.

As a matter of fact, experience teaches that, owing to such very small gaps, which of course require a high degree of accuracy in the machining of the conductor parts and in the centering of the elements in relative rotation with respect to each other (one of these elements being for instance stationary and the other rotating about it), it becomes unnecessary to provide friction contacts in the atmospheric air (or any other gas) in which the apparatus is located. Furthermore, the friction of air on the rotating element creates an electrical unbalance which is generally suflicient to provide for the starting of the machine.

If one set of conductor parts is carried by a fixed element and the other set is carried by a rotating element, this last mentioned set is advantageously disposed on the outside of the first set, whereby if radial expansion is caused by high speed rotation of the rotating element, this expansion has for its effect to increase the gap initially provided between the two sets of conductor parts.

These features apply to machines the elements of which are constituted by discs or by cylinders. I will now describe an embodiment in which the machine includes two coaxial cylinders one of which surrounds the other.

The rotor of this machine includes a metallic sleeve 11, acting as a fly-wheel, and an insulating ring 3 in which are embedded two collecting parts 1 and 2 constituted by plates having the shape of portions of cylindrical surfaces. The direction of rotation of this element is indicated by arrow 1. The stator includes a cylindrical insulating mass 8 at the periphery of which are disposed a plurality of influenced plates opposed two by two, 4a and 4b, 5a and 5b, 6a and 6b, 7a and 7b.

In order to earth, that is to say to connect to metallic part 11 the influenced plates 4a4b, 5a5b, etc., I provide two opposed bars 19a and 19b in contact with said metallic part 11 and insulated from plates 1 and 2. In order to transfer the electric charges thus formed in the influenced plates onto collecting plates 1 and 2, I provide two opposed bars 20a and 20b in contact with said plates 1 and 2. According to my invention, the machine is arranged in such manner that the gap between bars 19a and 19b, 20a and 20b and the influenced plates 4a4b, 5a5b, etc., when they come opposite them, is extremely small but never equal to zero, averaging preferably 0.02 mm.

Of course, the fact that this gap is extremely small involves the necessity of a very accurate construction. The machining of stator 8 is for instance performed after plates 4a-4b, Sa-Sb, etc., have been already fixed there to. Likewise, the whole of bars 19a and 19b, 20a and 20b can be machined after said bars have been fixed to the rotor. Furthermore, the bearings of this rotor will be made very carefully.

The machine works in the following manner. Initially, the two plates 1 and 2 are charged with electricity of opposed polarities. For instance, plate 1 carries a negative charge and plate 2 a positive one. Every influenced plate 4a, 4b, 5a, 5b, etc., when it comes opposite collecting plates 1 and 2 is simultaneously earthed, that is to say connected with metallic part 11, through bars 19a-- 1%. In these conditions, the two-opposed plates 4a and 4b for instance, which are in this position are charged with electricity of opposed polarities respectively. When these plates, for instance 4:: and 4b, come, due to the rotation of parts -113, opposite bars 20a and 201), they discharge through said bars into the collecting plates 1 and 2. Thus, the charges of these two plates '1 and 2 are constantly increased and the machine is of the multiplication type. But there is never any contact between parts rotating with respect to each other and the discharge of electric charges takes place through a layer of a gaseous dielectric of a very small thickness e.

Theelectric connection between the rotor and the spark plug may also take place through a layer of a gaseous dielectric, by providing for instance a projection 17 connected with one of the'collecting plates, 1 for instance,

and a fixed metallic rod 18 disposed at a small distance from the trajectory of the end of projection 17.

In a general manner, while I have, in the above de- 30 the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

1. A rotary electrostatic machine working by influence which comprises two coaxial elements rotatable with respect to each other and a plurality of cooperating electric charge transferring conductor parts rigidly carried by said elements respectively and insulated from one another, two conductor parts mounted to cooperate together being adjusted to run with a gap between them lower than 0.08 mm.

2. A machine according to claim 1 in which the gaps between said cooperating conductor parts range from 0.02 to 0.04 mm.

3. A rotary electrostatic machine'working by influence which comprises two coaxial elements, one fixed and the other rotatable, a set of conductor parts carried by the inner fixed element and insulated from one another and a set of conductor parts carried by the outer rotating element and insulated from one another, for cooperating with the first mentioned conductor parts for transferring electric charges from parts of one set to parts of the other set, the two sets of parts being adjusted to run with a gap between them lower than 0.08 mm., the second mentioned set being located externally, in the radial direction, of the first mentioned set.

References Cited in the file of this patent UNITED STATES PATENTS I 

